Monidirectional range system



Oct. 2, 1956 Filed Aug. 1, 1952 A. ALFORD OMNIDIRECTIONAL RANGE SYSTEM 2 Sheets-Sheet 1 GUN/OMETER COIL 4E 42, FIE-.1

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Amw A/my Oct. 2, 1956 A.- ALFORD OMNIBIRECTIONAL RANGE SYSTEM 2 Sheets-Sheet 2 Filed Aug. 1, 1952 INVENTOR. flhdrgw Unite States The present invention relates to an omnidirectional range system including in combination a radiating antenna and means for exciting the same so that it radiates two figure of eight patterns at right angles to each other and a circular pattern which has an intensity at least the equivalent of the figure of eight intensity.

In the present invention the radio antenna may vary in construction providing the effective radiation pattern is produced. The system contemplates the combination of suitable radiating antennas energized through coaxial bridges of the type described in my copending patent application Serial No. 175,694, filed July 25, 1950, and a goniometer of any type adaptable to the frequency range which will cause a continuous sinusoidal variation of the energy radiated by the antennas relative to the north,

south, east and west directions of the antennas.

One of the purposes of the present invention is the development of an omnidirectional range system which may be stationary in character, except for the use of a goniometer to provide the rotation of the figure-of-eight pattern.

A further advantage of the present system is that a single supply source may be used both for the goniometer and for the circular feed and that by the use of the coaxial bridges above mentioned, the antenna may be fitted directly through the bridges in a comparatively simple arrangement.

Other and further advantages of the present invention will be more readily understood from the description set forth in the specification below when taken in connection with the drawings illustrating an embodiment thereof in which:

Figure 1 shows schematically the arrangement of the system;

Figure 2 shows in perspective the construction of the radiating antenna.

aren't O Figure 3 is a section centrally through the radiation antenna.

Figures 4, 5 and 6 show schematically radiation patterns of the radiator.

' Figure 7 shows a modification of the arrangement shown in Figure 3.

Figure 8 shows another form of the radiator which may be used in the present invention.

I Figure 9 shows schematically the arrangement of the radiator of Figure 8, in the system; and

Figure 10 shows diagrammatically a general transverse section through the radiator of Figure 8.

As shown in the somewhat schematic diagram of Figure 2, the antenna of this invention comprises a metal vmast of tube 1, which may be stationary with its axis extending in a vertical direction providing a vertically ,polarized system to which are secured in any suitable manner, making electrical connections therewith, two similar metallic members 2 and 3 which have the general shape of pie-plates one of which is inverted with fiat surfface walls 4 and ring-like rim portions 5. The dished portionsof the pie-plate face one another and are in planes substantially perpendicular to the plane of the metal mast 1 which passes through the central axis of the elements 2 and 3. The antenna itself in structure is similar to that disclosed in my issued United States Patent No. 2,508,084, patented May 16, 1950. It may be described as a hollow cylinder with closed ends and an air gap around the middle. The edge portions of the two ring elements 5 are placed opposite each other to form a fairly narrow air gap 6 which extends continuously around the ring like portions 5, between adjacent edges of the ring. The space 7 within the cavity formed by the elements 2 and 3, the air gap 6 and axial collars 50 and 51 (Figure 3) which surround the mast or tube 1 has a shape of a toroid. The width and length of the gap, the cross sectional area and volume of the cavity follow the dimensions which are outlined in my patent mentioned above. The metallic tubes 8, 9, 10 and 11 are secured to the top ring of the hollow cylinder half or elements 2 by bolting, welding or any other suitable means to provide good electrical connec tions with these elements. Similarly metallic tubes 12, 13, 14 and 15 are secured to the lower cylinder half or shell 3. While in Figure 2, both elements 2 and 3 are illustrated as cylindrical in shape, other shapes may be used as for instance regular polygons and possibly ovals in some cases all of which are intended to be included in the notation of cylindrical or pre-shaped shells.

Four coaxial feeders 16, 17, 18 and 19 are connected so as to apply a high frequency potential across the continuous air gap 6 between adjacent edges of the rings 5, 5. These coaxial feeders pass through the mast or tube 1 through the top plate 4 of the elements 2 through holes about apart downward adjacent the ring 5 with which the outer conductor of the coaxial feeder is preferably in contact at least at the edge of the ring as shown in Figure 3 but it may be in contact all the way across the ring. The outer conductors 20, 21 and 22, 23 (not shown in Figure 2) but continuous with the outer con- .ductor of the coaxial cables 17 and 18 respectively, are

all connected to the shell'2 along the side rings 5, while the inner conductors 25, 26 and 27, 28 (not shown in Figure 2) are connected across the gap 6 to the ring 5 of the lower ring of member 3, thus forming four points of feed across the air gap acting as a transmission line 8, 13. When all four coaxial feeders are energized in the same relative phase a nearly uniform R. F. potential is produced across the gap 6.

This radio frequency potential is effectively applied between the adjacent facing ends of the metal tubes or rods 8 and 13; 9 and 12; 10 and 15; and 11 and 14; respectively, so that the four pairs of tubes which are substantially axially aligned in pairs become excited as four dipoles. Under these conditions the currents in these four pairs of tubes or rods are then equal to each other and in The radiation pattern of the scribed, is almost perfectly circular in the horizontal planes when the axis of the mast is vertical.

When only a pair of opposite coaxial feeders, such as, for example, feeders 1'8 and 16 are energized in phase opposition, while the second pair of feeders, 17 and 19 are not energized, a distribution of potential across the 'gap 6 is roughly sinusoidal with the maximum of potential at one of the two energized feeders, such as 16, and

an equal maximum potential of opposite polarity at the other energized feeder, such as 18. The two nulls in this sinusoidal distribution are then opposite the other two not energized feeders 17 and 19. Under such conditions two pairs of dipoles such as 11, 14 and 8, 13 are energized equally and in the same relative phase, while the other two pair of dipoles 10, 15 and 9, 12 are energized equally but in a phase opposite to that of the first two dipoles. The radiation pattern with this method of excitation is a figure-of-eight whose maxima are along the line which joins the points at which the energized feeders pass across the gap 6. The nulls of the figureof-eight pattern are along the line which passes through the energized feeders as they cross the gap 6.

It is thus seen that by energizing one pair of feeders, such as 16, 18, it is possible to obtain a figure-of-eight radiation pattern with a max-ima, say in the direction of north and south. And by energizing the other pair of feeders 17, 19, it is possible to get another figure-of-eight radiation pattern with maxima in the direction of east and west. This refers to a stationary position of the elements without the use of a goniometer.

Consider now Figure l of the drawings. In this figure the circle 27 is a schematic representation of the rings of the elements 2 and 3. The feed lines marked by 16, 17, 18 and 19 represent the same correspondingly numbered elements in Figure 2. Elements 28 and 29 are coaxial bridge circuits which are described in my copending application S. N. 175,694, referred to above. 43 indicates a high frequency terminal or supply source which is connected by means of a coaxial line 31 to the input A of the coaxial bridge 29. A similar connection is made by means of the coaxial feeder 30 to the input A of the coaxial bridge circuit 28. The coaxial bridge circuits described in the application above referred to have the propertythat when a proper high frequency source is connected to the input A, and A, respectively, equal loads 1 and II connect to the outputs C and D respectively, of each coaxial bn'dge receive equal potentials in the same relative phase, while no potential is developed between the inner and outer conductors of the coaxial input ter minals of both B and B respectively; that is, the power out of the coaxial bridge at both input terminals B and B is zero.

When the same circuits are energized by connecting a coaxial feeder to terminals B or B loads I and II of the coaxial bridge circuits are energized by potentials which are equal but opposite in phase; that is, the potential at C is equal and opposite in phase to the potentials at D.

It is desirable to make the feeders 30 and 31 to the input A and A respectively of the coaxial bridge circuits of equal length so that the relative phases developed at the source 43 will be preserved at the inputs A and A of the coaxial bridge.

Two pairs of output terminals of the two bridges are connected to the coaxial feeders which are represented by lines corresponding to the coaxial cables 16, 17, 18 and 19 of Figure 2. When the system is energized by connecting a source of R. F. power to the coaxial terminal 43, feeders 16, 17, 18 and 19 are all energized with equal power in the same relative phase. If the length in these feeders are equal then the potential applied by the four feeders across the gap 6 are equal and in the same relative phase. The result of this arrangement is that when the system is so energized, a circular radiation pattern 32 (Figure 4) is produced in the horizontal plane.

By energizing the coaxial cable 33 to the input B of the bridge "28 through a goniometer 52 connected to the terminal 42 for modulating the R. F. or carrier sinusoidally, the coaxial feeders 16 and 18 are energized by equal potentials which are in opposite phase and similarly by energizing the coaxial feeder-s 34 connected to the input B of the bridge 29, through the goniometer source 52 connected to the terminal 41, likewise the coaxial feeders 17 and 19 are energized by equal potentials which are opposite in phase and are apart respectively from the energization through the feeders 16 and 18. Thus when a source of R. F. power is connected to the coaxial terminal 42 of feeder 33, a figure-of-eight radiation pattern 54 (Figure 5) is produced. Similarly when a source of R. F. power is connected to terminal 41 of feeder 34 which is connected to the coaxial terminal of bridge 29, a figure-of-eight radiation pattern 55 (Figure 6) is produced.

The goniometer source 52 may be of any of the usual esigns in which the R. carrier is modulated sinusoidally and fed over the line 41' to the terminal 41 and a corresponding potential is supplied over the line 42' to the terminal 42. Each of these potentials should vary sinusoidally with the same wave shape but 180 out of phase with one another. The figure-of-eight radiation patterns as indicated by the small patterns 54, and 55 respectively will be provided in one case, the maximum being in a north, south direction, when the pattern of the other case is in an east and west direction. By rotating the goniometer coil, 56, about an axis perpendicular to the plane of the paper it will be seen that there will be a maximum in a north-south direction in one position of the coil 56, at the time that there is a minimum in the east-west direction.

In normal operation, feeders 33 and 34 are made equal lengths. The potential delivered to feeder 33 is modulated in proportion to cos (2 FE) while the potential delivered to feeder 34 is modulated in proportion of sin (2 FE) where F is the frequency of goniometer rotation. The effect of such modulation is to produce in space not two independent figure-of-eight patterns but one fiure-of-eight pattern which rotate at the same frequency as the goniometer.

If R. F. power of the same frequency and from a synchronized source is fed to the terminal 43, While terminals 41 and 42 are energized through the goniometer rotating, radiation pattern can be produced in space provided that the length of the feed between terminal 43 and the source of R. F. power has been adjusted in length until the phase of signal radiated in the form of the circular pattern 32 'is in the same phase in the north lobe of pattern '54 and the relative amplitude of the signal in the circular pattern 32 is greater than the maximum signal in the figureof-eight pattern.

In the arrangement indicated in Figure 3, the collars or sleeves 50 and 51 are ShOWn as fitting the mast 1. These sleeves may be metallic and may be bolted or secured to the mast in any suitable manner.

A modified construction of the unit of Figure 3 is shown by the section of Figure 7. Here the two half cylindrical or pie-shaped elements 60 and 61 are formed with central axial sleeves 62 and 63 respectively through which the sections 60 and 61 may be secured by bolts 64 and 65 respectively to the mast 1. The central sleeves are however connected by channel sections 66 and 67 respectively to the rest of the half cylindrical elements together forming the toroid like cavity 68 which is surrounded by the cylindrical air gap 69. The rest of the construction comprising the dipole. positions and construction, the manner of feed, and the connections of the coaxial cables is the same as in the other figures.

The applicant has successfully used an antenna construction shown in Figure 7 at approximately megacycles in which the, structure had the following dimensions. The length of the dipole rods, a, was 21" corresponding to 206x. The width of the air gap, b, was equal to 2 corresponding approximately to .02391. The distance between the top end of the cylinder and the bottom end of the cylinder, c, was equal to 15 or approximately l.487\. The distance, d, between the inner surfaces of the cavity was equal to. 14" corresponding approximately .138A. The diameter across the cylinder on the outside, e, was equal to 31% or approximately .313) The diameter of the dipole rods, g, was the. equivalent to 1%."

of approximately .0148A and the diameter of the mast. m was approximately /2" or equivalent to .0493) The dimensions of the unit are not too critical, and the dimensions may vary providing the pattern indicated in Figures 4, 5 and 6 are substantially maintained. In the arrangement above described, the antenna shown provides four pairs of dipoles positioned about a circle 90 apart from each other with the dipole rods all parallel to each other.

The arrangement indicated in Figures 8, 9 and employ an antenna or radiator of the type described in the cavity, application of Robert M. Sprague S. N. 284,680, filed April 28, 1952.

Figure 8 shows a cylindrical radiator of the type described in said application in which there is provided four parallel slots S1, S2, S3, and S4 in the wall of a cylindrical radiator all parallel to the axis of the cylinder and spaced 90 apart from each other. The operation of this cylindrical radiator has been described fully in the application above referred to. Such a cylinder may be used in the same manner as the antenna described above in connection with the circuit set forth herein. The diagrammatic arrangement of this circuit is shown in Figures 9 and 10 to which the same numerals have been applied as in the arrangement shown in Figure 1 since the elements having the-same corresponding numerals are the same type elements. Two opposite pairs of slots as for instance S1, S3 and S2, S4 are energized by coaxial cables 19 and 17 respectively connected across the slots. The slots S2 and S4 are similarly energized by the coaxial cables 16 and 18 connected respectively across the slots.

The coaxial cables 16 and 18 are energized through the coaxial bridge 28 and the coaxial cables 17 and 19 through the coaxial bridge 29. The circular feed similarly as in Figure 1 is supplied through the terminal source 43 over the coaxial cables 30 and 31 to the inputs A and A of the coaxial bridges 28 and 29. The figure-of-eight feeds are supplied through the figure-of-eight terminal sources 41 and 42 respectively connecting to the input terminals B1 and B of the coaxial bridges 29 and 28. A comparison will show that the arrangement for Figure 9 is the same as the arrangement shown in Figure 1 and that as a result the four slots S1, S2, S3, and S4 are energized in the same phase for the circular feed and in phases which have opposite potentials for the figure-ofeight feed providing two pairs of opposite excitation for the slots 90 apart from each other. Figure 10 shows a schematic cross sectional view of the connection of the coaxial cables 16, 17, 18 and 19 across the slots S2, S3, S4 and S1 respectively. The outer conductors of these cables are connected at one side of the slot and the inner conductors are taken across the gap or slot to the other side of the cylinder. In either of the arrangements described the goniometer of the type shown in Figure 1 or any other suitable goniometer will be used to rotate continuously the phase of the figure-of-eight patterns while the circular pattern will always preserve its constant effect.

It will be noted of course that the radiator of Figures 8, 9 and 10 will produce, when the axis of the cylinder is arranged vertically, a horizontally polarized wave.

Having now described my invention I claim:

1. An omnidirectional range system including means for radiating electromagnetic waves at four spaced positions with respect to a common central point, means for supplying to such means at said four spaced positions, high frequency electromagnetic waves modulated with phase angles substantially 90 apart from each other and means for energizing such first means at said four spaced positions simultaneously with high frequency electromagnetic waves all in the same phases.

2. A system as set forth in claim 1 in which said energizing means have a common supply source of a single frequency.

3. A system as set forth in claim 1 in which said energizing means have the same frequency.

4. .A system as set forth in claim 1 in which said means for supplying high frequency electromagnetic waves coniprises means for supplying two figure-of-eight wave patterns at right angles to each other.

5. A system as set forth in claim 1 in which said last energizing means comprises a feed having a circular pattern supplying energy at said four spaced positions in the same phase.

6. A system as set forth in claim 1 in which said last energy means has a maximum potential at least as great as the maximum potential of any of the phases at right angles to each other.

7. A system as set forth in claim 1 in which said four spaced positions are supplied with high frequency electromagnetic waves by means including two coaxial bridges each having two outputs and an input the outputs of each coaxial bridge having opposing phases and means supplying the inputs with waves modulated 90 out of phase with each other.

8. A system as set forth in claim 1 in which said four spaced positions are supplied with high frequency electromagnetic waves by means including two coaxial bridges each having two outputs and an input the outputs of each coaxial bridge having opposing phasessaid inputs being supplied with high frequency electromagnetic waves modulated with phase differences of 90 with each other.

9. A system as set forth in claim 1 in which said four spaced positions are supplied with high frequency electromagnetic waves by means including two coaxial bridges each having two outputs and two inputs, the outputs of each coaxial bridge having opposing phases when supplied from one input and similar phases when supplied from the other input and means for supplying said inputs with said electromagnetic high frequency waves.

10. A system as set forth in claim 1 in which said four spaced positions are supplied with high frequency electromagnetic waves by means including two coaxial bridges each having two outputs and two inputs, the outputs of each coaxial bridge having opposing phases when supplied from one input and similar phases when supplied from the other input, means for supplying one of said one input of each coaxial bridge with said high frequency electromagnetic waves modulated 90 out of phase with the other of said magnets and means for supplying said other input of each coaxial bridge with said high frequency.

11. An omnidirectional range system comprising a radiator of electromagnetic waves having four spaced radiating sources with respect to a common central point, means for supplying high frequency electromagnetic waves at said four spaced radiating sources comprising two coaxial bridges each having two outputs and one input providing opposite phases at said outputs and a second input providing similar phases at said outputs, means connecting the outputs of each coaxial bridge to the two opposing spaced radiating sources, means energizing the first inputs with high frequency electromagnetic waves modulated 90 out of phase with one another and means energizing the second inputs with high frequency electromagnetic waves in phases with each other.

12. An omnidirectional range system comprising a radiator of electromagnetic waves having four spaced radiating sources with respect to a comm-on central point, means for supplying high frequency electromagnetic waves at said four spaced radiating sources comprising two coaxial bridges each having two outputs and one input providing opposite phases at said outputs and a second input providing similar phases at said outputs, means connecting the outputs of each coaxial bridge to the two opposing spaced radiating sources, means energizing the first inputs with high frequency electromagnetic waves modulated out of phase with one another including a goniometer for continuously modulating sinusoidally said high frequency electromagnetic waves and'rneans' energizing the seeond inputs with high; frequency eiectromagnetic wavesin phases with. each. other. i 13.. A system as set forth in claim l1= in which the means energizing said. first inputs produces two figure of-eightradia'tng patterns at rightanglesto each other and the means for energizing said secondinputs produce a circularradiation, the intensity bf said circularradi- 'atioxrpattern having an amplitude equal to that fifths.

maximum of said figure-of-eight radiation-patterns.

'14. A system asset forth in claim. 11in which the means energizing said first inputs produces two figureof-eight radiating patterns at right angles to each other and the means for'energizing said second. inputs produce a circular radiation, the intensity of said circular.

radiation pattern having'an amplitude equal to that cf the maximum ofsaid'figure-of-eight radiation patterns and a goniometerfor providing'a' continuous rctatisn gof said figures-of-eight patterns in the same relative po- I sitions with one ancther and the pairs modulated at; 9 0 part from each otherg RefereBces'Cited'i-n the file of this patent 1 I j V UNITED I STATES PATENTS 2,252,699 Byrne. ..4 Aug. 19, 2,253,958 Luck, L Aug. 26,.l941' 2,293,694 Alford; Aug. .25, .1942

,4l4,431 Alford et a1. Ian 21, 1947 2.422110. .Luck June 10, 19.47.

15. A system asset forth in claim 1 in. which Said {cur spaced positions are. supplied with high frequency electromagnetic Waves by means including two coaxial bridges eachhaving similar; inputs: having its radio fre-- quency' modulated 90? out of phase andsimiiar outputs, each output havingitwo' phases'opposite to one-another 

